This invention pertains to video generators and, more particularly, to such generators which generate color displays.
In such generators, it is possible to create color displays by controlling the colors to be generated along the lines of a conventional television raster. Such displays are associated with graphic generators as well as television signals which supplement conventional "live" pictures. In these generators, it has become the practice to digitally encode the colors as well as the run lengths along the horizontal lines of the raster. Heretofore, the coding was structured as a first word or byte indicating the color and a second word or byte indicating the length. The other possibility is to within a single word reserve a portion for the color information and the remainder for the length information. Such a scheme is inefficient when one realizes that most often the length of the element exceeds the length that can be represented by the word. For example, if the element length is two times the possible maximum length that can be defined by a word, it is necessary to use two words with each word, including both the color and one-half the length value. Furthermore, in many instances, it is possible that in any horizontal line of the raster the color may change only once for the whole sweep. If the color changes close to the start of the line, then it is necessary to transmit several words of the second color to fill out the line. There are other wasteful operations when a single color is to be displayed for the whole frame or major portions thereof.